1. Field of the Invention
The present invention relates to a safety apparatus for pneumatic tires, and a method of mounting the apparatus onto a conventional tire rim. More particularly, the present invention relates to an apparatus that can support the weight of the rim and the vehicle to which it is mounted when the tire goes flat, so that the vehicle may be operated until the flat tire is replaced.
2. Description of the Prior Art
Pneumatic tires are the most common type of tires used today in the automobile and aircraft industry. Such tires rely on a compartment of compressed air to support the outer tread surface of the tire and to seal the tire against a wheel rim. The boundaries of the air compartment are formed by the inner surface of the tire and the outer surface of the rim. The outer surface of the rim commonly has an air passage formed therein which leads to an external air valve, so that the pressure of the air in the compartment may be regulated.
A disadvantage with such tires, however, is that they lose their ability to support the rim and the vehicle attached thereto when air pressure in the compartment falls beneath a certain level. This is especially dangerous, considering that sudden deflation of the compartment may occur if the tire is penetrated by a sharp object during operation of the vehicle. Such blowouts have caused many automobiles to go out of control and present a particularly dangerous problem for airplanes during takeoff and landing.
Previous attempts have been made to provide a safety device for supporting a pneumatic tire after its air compartments have lost pressure. Examples of such devices are disclosed in U.S. Pat. No. 3,141,490 to Lindley, U.S. Pat. No. 4,327,791 to Strader and U.S. Pat. No. 4,572,260 to Ordu. However, none of these devices appears to be both easily mountable to a convential pneumatic tire rim, and capable of preventing the tire from becoming separated after deflation.
For example, the tire support in Lindley has a narrow flat support surface spaced from the rim of the wheel for supporting the tire after deflation. It is clear that the structure in Lindley would be insufficient to prevent the tire from becoming separated from the wheel rim, since the tire could easily slip over the support surface once the tire is deflated. In addition, it would appear difficult to secure the support apparatus in Lindley to the rim of a wheel because of the number of parts involved.
The safety tire and wheel assembly in Strader includes a safety insert with an inner portion extending around a wheel rim base for clamping the beads of the tire against opposing rim flanges and an outer portion projecting radially into the tire cavity. The outer portion has a relatively narrow surface on which the tire may rest when flat. Although this arrangement would appear to prevent the tire from becoming separated from the rim, it would be difficult to mount a tire properly on such a device. In addition, it is doubtful whether this device is compatible with most of today's conventional wheel rims.
The Ordu device similarly appears to be incompatible with most of the vehicle wheels in use today, and would not appear to be particularly effective in preventing the tire from becoming separated from the rim.
Clearly, a long and unfilled need exists in the art for a safety device for use with a vehicle tire that is compatible with most of the wheel rims in use today and is effective in preventing the tire from becoming separated from the rim.